There is a warning out for Parkinson's disease patients taking the drugs Permax and Dostinex.
Researchers in North Carolina and Europe have found a link between the drugs and a heart condition.
One study found as many as 30 percent of people on Dostinex developed cardiac valve regurgitation, a condition where blood flows backward into the heart.
Experts at the University of North Carolina have found a cause.
They say the drugs stimulate a specific receptor in the heart related to the valve disease.
The experts say you should talk to your doctor about the risk if you are on one of these drugs.
The valve disease can be deadly.